package bill.study.enums.effectivejava.item33;

import java.util.EnumMap;
import java.util.Map;

public enum Phase {
	SOLID, LIQUID, GAS;

	public enum Transition {
		MELT(SOLID, LIQUID), FREEZE(LIQUID, SOLID), BOIL(LIQUID, GAS), CONDENSE(
				GAS, LIQUID), SUBLIME(SOLID, GAS), DEPOSIT(GAS, SOLID);

		private final Phase src;
		private final Phase dst;

		Transition(Phase src, Phase dst) {
			this.src = src;
			this.dst = dst;
		}
	}

	private static final Map<Phase, Map<Phase, Transition>> m = new EnumMap<Phase, Map<Phase, Transition>>(
			Phase.class);
	static {
		for (Phase p : Phase.values()) {
			m.put(p, new EnumMap<Phase, Transition>(Phase.class));
			for (Transition trans : Transition.values()) {
				m.get(trans.src).put(trans.dst, trans);
			}

		}
	}

	public static Transition from(Phase src, Phase dst) {
		return m.get(src).get(dst);
	}
}
